Experimental investigation of waveform tip injection on the characteristics of the tip vortex

Download
2011
Ostovan, Yashar
This study investigates the effect of chordwisely modulated tip injection on the flow and turbulence characteristics of the tip vortex through experimental measurements downstream of a rectangular half-wing that has an aspect ratio of three. This injection technique involves spanwise jets at the tip that are issued from a series of holes along the chord line normal to the freestream flow direction. The injection mass flow rate from each hole is individually controlled using computer driven solenoid valves and therefore the flow injection geometrical pattern at the tip can be adjusted to any desired waveform shape, with any proper injection velocity. The measurements are performed in a blow-down wind tunnel using Constant Temperature Anemometry and Kiel probe traverses as well as Stereoscopic Particle Image Velocimetry. Current data show consistent trends with v previously observed effects of steady uniform tip injection such as the upward and outward motion of the vortex as well as increased levels of turbulence within the vortex core. The vortex size gets bigger with injection and the total pressure levels get reduced significantly near the vortex core. The injection pattern also seems to affect the size of the wing wake as well as the wake entrainment characteristics of the tip vortex. Depending on the injection waveform pattern and injection momentum coefficient the helicoidal shape of the tip vortex also seems to get affected.

Suggestions

AN IMPROVED 1D MODEL FOR LIQUID SLUGS TRAVELLING IN PIPELINES
Tijsseling, Arris S.; Hou, Qingzhi; Bozkuş, Zafer (2014-07-24)
An improved one-dimensional (1D) model - compared to previous work by the authors - is proposed which is able to predict the acceleration and shortening of a single liquid slug propagating in a straight pipe with a downstream bend. The model includes holdup at the slug's tail and flow separation at the bend. The obtained analytical and numerical results are validated against experimental data. The effects of the improvement and of holdup are examined in a parameter variation study.
Implementation and comparison of turbulence models on a flat plate problem using a Navier-Stokes solver
Genç, Balkan Ziya; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2003)
For turbulent flow calculations, some of the well-known turbulence models in the literature are applied on a previously developed Navier-Stokes solver designed to handle laminar flows. A finite volume formulation, which is cell-based for inviscid terms and cell-vertex for viscous terms, is used for numerical discretization of the Navier-Stokes equations in conservative form. This formulation is combined with one-step, explicit time marching Lax-Wendroff numerical scheme that is second order accurate in spac...
An Improved One-Dimensional Model for Liquid Slugs Traveling in Pipelines
TIJSSELING, Arris S.; Hou, Qingzhi; Bozkuş, Zafer (2016-02-01)
An improved one-dimensional (1D) model-compared to previous work by the authors-is proposed, which is able to predict the acceleration and shortening of a single liquid slug propagating in a straight pipe with a downstream bend. The model includes holdup at the slug's tail and flow separation at the bend. The obtained analytical and numerical results are validated against experimental data. The effects of holdup, driving pressure and slug length are examined in a parameter variation study.
Experimental investigation of the effects of different helicopter rotor tip geometries on aerodynamic performance and tip vortex characteristics
Uluocak, Sinem; Hazaveh, Hooman Amiri; Perçin, Mustafa; Akpolat, M Tuğrul; Uzol, Oğuz (Netherlands Association of Aeronautical Engineers; 2018-09-05)
In this study, the effects of different tip geometries (rectangular, anhedral, swept-tapered and swept-tapered-anhedral) on the rotor hover performance and tip vortex characteristics are investigated experimentally. A scaled rotor model set-up, instrumented with thrust and torque sensors, is used for aerodynamic performance measurements in hover and a two-dimensional (2D) particle image velocimetry (PIV) is used to obtain the tip vortex characteristics such as vortex trajectory, maximum tangential velocity,...
Direct numerical simulation of pipe flow using a solenoidal spectral method
Tugluk, Ozan; Tarman, Işık Hakan (2012-05-01)
In this study, a numerical method based on solenoidal basis functions, for the simulation of incompressible flow through a circular-cylindrical pipe, is presented. The solenoidal bases utilized in the study are formulated using the Legendre polynomials. Legendre polynomials are favorable, both for the form of the basis functions and for the inner product integrals arising from the Galerkin-type projection used. The projection is performed onto the dual solenoidal bases, eliminating the pressure variable, si...
Citation Formats
Y. Ostovan, “Experimental investigation of waveform tip injection on the characteristics of the tip vortex,” M.S. - Master of Science, Middle East Technical University, 2011.